Interplay of interactions, disorder and topology in the Haldane-Hubbard model

TL;DR

This paper explores how disorder, interactions, and topology interact in the Haldane-Hubbard model, revealing a disorder-driven topological transition and analyzing the nature of phase transitions with finite-size effects.

Contribution

It demonstrates the stability of the topological Anderson insulator against small interactions and analyzes the transition nature in disordered, interacting systems.

Findings

Disorder can induce a topological phase transition in the Haldane-Hubbard model.

Topological Anderson insulator remains stable with weak interactions.

Finite-size effects lead to mixed first and second order transition signatures.

Abstract

We investigate the ground-state phase diagram of the spinless Haldane-Hubbard model in the presence of quenched disorder, contrasting results obtained from both exact diagonalization as well as density matrix renormalization group, applied to a honeycomb cylinder. The interplay of disorder, interactions and topology gives rise to a rich phase diagram, and in particular highlights the possibility of a disorder-driven trivial-to-topological transition in the presence of finite interactions. That is, the topological Anderson insulator, demonstrated in non-interacting settings, is shown to be stable to the presence of sufficiently small interactions before a charge density wave Mott insulator sets in. We further perform a finite-size analysis of the transition to the ordered state in the presence of disorder, finding a mixed character of first and second order transitions in finite lattices, tied to specific conditions of disorder realizations and boundary conditions used.